A transformer is an apparatus that transforms AC voltage or AC current by using electromagnetic induction. A general transformer includes a bobbin-wound primary coil and a secondary coil and a core formed with a magnetic material in order to surround an inside and an outside of a bobbin. The transformer further includes a semiconductor switch part such as a field-effect transistor (FET), an insulated gate bipolar transistor (IGBT), and a diode.
Recently, studies have been performed to reduce the entire volume of the transformer. A magnetic part such as the core takes the most volume in the transformer. However, a temperature of the core is increased when the volume of the core formed with a magnetic substance is reduced.
According to the conventional art to solve the above problem, thermal grease is applied to a bottom surface of an assembly combined with a core and a bobbin. The assembly is mounted to a housing and fixed to the housing after a heat dissipating plate is mounted at an upper side of the assembly. According to the conventional art as described above, an external temperature of the bobbin and the core surrounding the bobbin is reduced, but heat generated from an inside of the core cannot be dissipated.
For another example, an assembly combined with a core and a bobbin is inserted into a case, a molding liquid having a high heat conductivity is poured into the case, and the molding liquid is hardened. According to the conventional art as described above, the manufacturing cost of a transformer is increased by using the case and the molding liquid, and the entire volume of the transformer is increased.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.